Abstract:SUMMARY The present study investigated the effect of using royal jelly (RJ) as protein source for the culture media that would be used in the nuclear maturation stage of bovine oocytes. Bovine ovaries were collected from local slaughterhouse and then the cumulus oocyte complexes (COCs) were recovered from visible antral follicles (2 to 8 mm) by aspiration method. The obtained COCs were examined under an inverted microscope. COCs with uniform cytoplasm and homogeneous distribution of cumulus cells were selected for in vitro maturation. COCs were randomly incubated in tissue culture media–199 (TCM-199) with 10% royal jelly (10RJ, n=179) and 10% fotal calf serum (0RJ, n=172 oocytes) for 22h at 39 ºC under 5% CO2 in humidified air at 95%. The nuclear maturation stages were determined by examining the oocytes under the inverted microscope. The proportion of oocytes reaching metaphase-I (MI) stage in the 0RJ and 10RJ groups was 19% and 20%, respectively. The rate of oocytes reaching the anaphase-I (AI) stage in both groups was determined as 2%. On the other hand, 1% of the oocytes developed up to the telephase-I (TI) stage in both groups. The maturation rate in 10RJ media (78%) was similar when compared with 0RJ media (77%). Methaphase-II (MII) stage oocytes the 10RJ media did not affect the expansion rates of cumulus cells when compared to 0RJ media. Similarly, the ratios in first polar bodies and the maturated oocytes cleaved to 2- cell 48h post activation and were not affected by the use of 10RJ in the culture media. Therefore, these results suggest that royal jelly (%10) can be used as a protein source in the in vitro maturation (IVM) of bovine oocytes. This study has shown that it will contribute to the studies to be carried out by identifying different protein sources in the in vitro maturation stage. The present study investigated the effect of using RJ as protein source for the culture media that would be used in the nuclear maturation stage of bovine oocytes. KEY WORDS Bovine, oocytes, IVM, royal jelly, parthenogenetic activation.